POS1305 ULTRA-HIGH-FREQUENCY ULTRASOUND FOR THE EVALUATION OF SKIN INVOLVEMENT IN SYSTEMIC SCLEROSIS: PRELIMINARY RESULTS OF A MONOCENTRIC STUDY
Authors: Y. Ferraioli, M. Fogante, D. Benfaremo, G. Argalia, G. Moroncini
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Cutaneous involvement is one of the most important clinical aspects of systemic sclerosis (SSc) and is characterized by three different phases in temporal sequence: oedematous, fibrotic and atrophic. The most widely used method to evaluate skin involvement is the modified Rodnan Skin Score (mRSS), which assigns a grade from 0 (normal) to 3 (severe) in 17 different areas of the body. However, the intra- and inter-operator variability of mRSS is considerably high. Thus, a more objective, sensitive and reproducible method for measuring skin involvement in SSc would be needed, both for clinical trials and for daily clinical practice. <h3>Objectives</h3> To evaluate the possible role of ultra-high-frequency skin ultrasound in patients with SSc. <h3>Methods</h3> Consecutive SSc patients fulfilling ACR/EULAR classification criteria were enrolled in this cross-sectional study. Patients with active immunosuppressive (IS) treatment were not excluded. Subjects with idiopathic Raynaud's phenomenon (RP) and healthy controls (HC) were also evaluated upon informed consent. All subjects underwent US evaluation, using a 70 MHz ultra-high frequency (UHF) probe, by an experienced radiologist, blinded to the clinical characteristics of the patients and controls, at six anatomical sites (forearm right and left, hand right and left, second finger right and left). The thickness of the dermis, epidermis and hypodermis was measured at each site, and the mean value between the right and the left side was used (Figure 1). Differences between groups were analysed using the ANOVA. The Pearson coefficient was used to evaluated correlations between variables. <h3>Results</h3> Sixty-two (62) SSc patients (43 limited cutaneous (lc) and 19 diffuse cutaneous (dc) SSc), 14 RP and 16 HC were enrolled. Patients with RP were significantly younger than SSc and controls. Mean disease duration of SSc was 9.74 years. 27% of patients were on active IS treatment, 30% were using bosentan and 48% intravenous prostanoids. UHF-US allowed a precise identification and measurement of the thickness of the dermis and hypodermis of all individuals. The mean dermal thickness in the fingers was significantly higher in dcSSc patients than in lcSSc, RP and HC (p&lt;0.001), while in the hands it was significantly higher only compared to RP (p&lt;0.001) and in the forearm there was no difference between groups. Dermal thickness at the finger level significantly correlated with age (r 0.28, p=0.0067) and mRSS (r 0.29, p=0.01). We found no differences in dermal thickness of SSc patients according to use of IS treatment. Hypodermal thickness of the hands and fingers was higher only in patients with lcSSc compared to all other groups but was also significantly correlated to age (r 0.31 and 0.22, p&lt;0.05, respectively) and BMI (r 0.36 and 0.32, p&lt;0.001, respectively). Hypodermal thickness of the fingers was lower in patients using bosentan treatment (p=0.01). <h3>Conclusion</h3> These data show that skin UHF-US allows to measure in detail the dermal thickness and that these measurements correlate with the skin score. UHF-US could be used as an objective, sensitive and reproducible method for measuring skin involvement in SSc. <h3>Reference</h3> [1]Clements PJ, et al. Skin thickness score in systemic sclerosis: an assessment of interobserver variability in 3 independent studies. J Rheumatol. 1993 Nov;20(11):1892-6. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.